1. Field of the Invention
The present invention pertains to a lens barrel used in a camera.
2. Description of the Related Art
Lens shutter cameras are widely used because of their compact size, ease of use and portability. It is common to use a plastic cylinder for the lens barrel used in this type of camera. Since there is an increasing demand for further reductions in the size of such lens shutter cameras in recent years, it is necessary to make the lens mount smaller.
However, when the lens diameter, shutter aperture diameter, etc. are fixed, the size of the outer diameter of the lens mount is determined almost entirely by the number of zoom units used. While it is possible to make the lens mount thinner in order to achieve further compactness, this would mean a reduction in strength. In order to increase the strength, U.S. Pat. No. 5,289,221 proposes the application of a steel sheet to the outer surface of the lens mount. However, a seam of the sheet would run along the length of the lens mount in the direction of the optical axis in this method, which is not preferred because it reduces the quality of its appearance.
In addition, where zoom lenses driven by cams are concerned, since it is necessary to form cam grooves, etc. on the inner side of the lens mount, if the thickness of the wall beneath the bottoms of the cam grooves is excessively reduced, the effectiveness of the wall in shielding light will be hindered and the configurations of the cam grooves will be seen in the appearance of the lens mount due to the change in the thickness of the wall beneath the cam groove bottoms, making it difficult to ensure the quality of the lens mount's appearance.